17 Glossary Terms starting with s

Word

Description

Security Element

The plant including track, associated with any reporting, interlocking and/or signaling for that track. Also called simply "plant."

Select

Select is the term used by Digitrax for choosing a locomotive address to run on a throttle. All Digitrax throttles have either a LOCO or SEL key that is used to initiate locomotive address selection. Typically press LOCO or SEL, enter the address number you want to run and press LOCO or SEL again to Select the locomotive address to run on a throttle knob.

Selectable

A DCC decoder is selectable when it is not currently in-use on another throttle.

Service Mode Programming

Service mode programming information sent by the command station or programmer as a broadcast signal that goes out to all decoders on the track. Some command stations have separate packet generators to provide independent service mode programming outputs so that the layout can continue operating while decoders are programmed. Others require that the layout be shut down and the packet generator be used for programming decoders.

Short Address

7 bit address, baseline packet format address.

Slot

A memory location in the command station that holds an active decoder address.
The the slots in a command station are sometimes referred to as the locomotive roster.

Slot Following

When more than one DT Throttle is logged on to a single loco address, both DT Throttles will be controlling that address and both DT Throttle displays will be updated with the same information. In other words, both operators will see what the other is doing.

Speed Stabilization

The use of back EMF by a decoder to modify power to the motor to keep speed constant. Speed stailisation can also be scaled to make the feature more useful. It's like "cruise control for your loco."

Speed Steps

Because DCC is a digital system, locomotive speeds are defined by discrete speed steps. DCC systems typically offer 14, 28 or 128 speed steps. This means that as motor voltage is increased that the speed of the locomotive increases in a straight line from stop to full speed with discrete speed values at each voltage.

Split Field Motor

Another term for AC motor.

Stall Current

The max current draw in amps for a motor when it is stalled. This is important in determining which decoder to install in a locomotive.

Standard Mode (14 Speed Step Mode)

The motor voltage/speed curve of the DCC loco from stop to full speed has 14 discrete speed steps. This means that speed control will be limited to just 14 steps. 14 speed step mode gives reasonably good speed control. Increasing to 28 speed step operation will give much better speed control and going to 128 speed step operation will give really excellent speed control. Standard mode is offered in most command stations because there are many decoders on the market that are not capable of 28 or 128 step mode.

Standards

Standards cover many aspects of interchange for model railroading. The DCC Standards

Start Voltage

Start Voltage or V-Start is the voltage added to the motor drive voltage at the first speed step. This adjustment allows you to trim the loco to compensate for its motor efficiency.

Stationary or Accessory Decoder

The electronic device used for turnouts and other accessories that receives the signal from the command station through the track, decodes it & tells the turnout or other accessory what to do.

Status Editing Decoders

A DCC decoder's status can be manually changed by a Digitrax command station at any time the decoder is selectable.

Stealing a Loco

This procedure allows a DT Throttle user to override the in-use interlock and force the throttle to log on to an in-use loco. This can result in having two throttles logged on to and controlling one address. See also Slot Following.